fs/btrfs/inode-map.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/delay.h>
  20 #include <linux/kthread.h>
  21 #include <linux/pagemap.h>
  22
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "free-space-cache.h"
  26 #include "inode-map.h"
  27 #include "transaction.h"
  28
  29 static int caching_kthread(void *data)
  30 {
  31         struct btrfs_root *root = data;
  32         struct btrfs_fs_info *fs_info = root->fs_info;
  33         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
  34         struct btrfs_key key;
  35         struct btrfs_path *path;
  36         struct extent_buffer *leaf;
  37         u64 last = (u64)-1;
  38         int slot;
  39         int ret;
  40
  41         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
  42                 return 0;
  43
  44         path = btrfs_alloc_path();
  45         if (!path)
  46                 return -ENOMEM;
  47
  48         /* Since the commit root is read-only, we can safely skip locking. */
  49         path->skip_locking = 1;
  50         path->search_commit_root = 1;
  51         path->reada = 2;
  52
  53         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
  54         key.offset = 0;
  55         key.type = BTRFS_INODE_ITEM_KEY;
  56 again:
  57         /* need to make sure the commit_root doesn't disappear */
  58         mutex_lock(&root->fs_commit_mutex);
  59
  60         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  61         if (ret < 0)
  62                 goto out;
  63
  64         while (1) {
  65                 if (btrfs_fs_closing(fs_info))
  66                         goto out;
  67
  68                 leaf = path->nodes[0];
  69                 slot = path->slots[0];
  70                 if (slot >= btrfs_header_nritems(leaf)) {
  71                         ret = btrfs_next_leaf(root, path);
  72                         if (ret < 0)
  73                                 goto out;
  74                         else if (ret > 0)
  75                                 break;
  76
  77                         if (need_resched() ||
  78                             btrfs_transaction_in_commit(fs_info)) {
  79                                 leaf = path->nodes[0];
  80
  81                                 if (WARN_ON(btrfs_header_nritems(leaf) == 0))
  82                                         break;
  83
  84                                 /*
  85                                  * Save the key so we can advances forward
  86                                  * in the next search.
  87                                  */
  88                                 btrfs_item_key_to_cpu(leaf, &key, 0);
  89                                 btrfs_release_path(path);
  90                                 root->cache_progress = last;
  91                                 mutex_unlock(&root->fs_commit_mutex);
  92                                 schedule_timeout(1);
  93                                 goto again;
  94                         } else
  95                                 continue;
  96                 }
  97
  98                 btrfs_item_key_to_cpu(leaf, &key, slot);
  99
 100                 if (key.type != BTRFS_INODE_ITEM_KEY)
 101                         goto next;
 102
 103                 if (key.objectid >= root->highest_objectid)
 104                         break;
 105
 106                 if (last != (u64)-1 && last + 1 != key.objectid) {
 107                         __btrfs_add_free_space(ctl, last + 1,
 108                                                key.objectid - last - 1);
 109                         wake_up(&root->cache_wait);
 110                 }
 111
 112                 last = key.objectid;
 113 next:
 114                 path->slots[0]++;
 115         }
 116
 117         if (last < root->highest_objectid - 1) {
 118                 __btrfs_add_free_space(ctl, last + 1,
 119                                        root->highest_objectid - last - 1);
 120         }
 121
 122         spin_lock(&root->cache_lock);
 123         root->cached = BTRFS_CACHE_FINISHED;
 124         spin_unlock(&root->cache_lock);
 125
 126         root->cache_progress = (u64)-1;
 127         btrfs_unpin_free_ino(root);
 128 out:
 129         wake_up(&root->cache_wait);
 130         mutex_unlock(&root->fs_commit_mutex);
 131
 132         btrfs_free_path(path);
 133
 134         return ret;
 135 }
 136
 137 static void start_caching(struct btrfs_root *root)
 138 {
 139         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 140         struct task_struct *tsk;
 141         int ret;
 142         u64 objectid;
 143
 144         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 145                 return;
 146
 147         spin_lock(&root->cache_lock);
 148         if (root->cached != BTRFS_CACHE_NO) {
 149                 spin_unlock(&root->cache_lock);
 150                 return;
 151         }
 152
 153         root->cached = BTRFS_CACHE_STARTED;
 154         spin_unlock(&root->cache_lock);
 155
 156         ret = load_free_ino_cache(root->fs_info, root);
 157         if (ret == 1) {
 158                 spin_lock(&root->cache_lock);
 159                 root->cached = BTRFS_CACHE_FINISHED;
 160                 spin_unlock(&root->cache_lock);
 161                 return;
 162         }
 163
 164         /*
 165          * It can be quite time-consuming to fill the cache by searching
 166          * through the extent tree, and this can keep ino allocation path
 167          * waiting. Therefore at start we quickly find out the highest
 168          * inode number and we know we can use inode numbers which fall in
 169          * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
 170          */
 171         ret = btrfs_find_free_objectid(root, &objectid);
 172         if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
 173                 __btrfs_add_free_space(ctl, objectid,
 174                                        BTRFS_LAST_FREE_OBJECTID - objectid + 1);
 175         }
 176
 177         tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
 178                           root->root_key.objectid);
 179         BUG_ON(IS_ERR(tsk)); /* -ENOMEM */
 180 }
 181
 182 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
 183 {
 184         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 185                 return btrfs_find_free_objectid(root, objectid);
 186
 187 again:
 188         *objectid = btrfs_find_ino_for_alloc(root);
 189
 190         if (*objectid != 0)
 191                 return 0;
 192
 193         start_caching(root);
 194
 195         wait_event(root->cache_wait,
 196                    root->cached == BTRFS_CACHE_FINISHED ||
 197                    root->free_ino_ctl->free_space > 0);
 198
 199         if (root->cached == BTRFS_CACHE_FINISHED &&
 200             root->free_ino_ctl->free_space == 0)
 201                 return -ENOSPC;
 202         else
 203                 goto again;
 204 }
 205
 206 void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
 207 {
 208         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 209         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 210
 211         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 212                 return;
 213
 214 again:
 215         if (root->cached == BTRFS_CACHE_FINISHED) {
 216                 __btrfs_add_free_space(ctl, objectid, 1);
 217         } else {
 218                 /*
 219                  * If we are in the process of caching free ino chunks,
 220                  * to avoid adding the same inode number to the free_ino
 221                  * tree twice due to cross transaction, we'll leave it
 222                  * in the pinned tree until a transaction is committed
 223                  * or the caching work is done.
 224                  */
 225
 226                 mutex_lock(&root->fs_commit_mutex);
 227                 spin_lock(&root->cache_lock);
 228                 if (root->cached == BTRFS_CACHE_FINISHED) {
 229                         spin_unlock(&root->cache_lock);
 230                         mutex_unlock(&root->fs_commit_mutex);
 231                         goto again;
 232                 }
 233                 spin_unlock(&root->cache_lock);
 234
 235                 start_caching(root);
 236
 237                 if (objectid <= root->cache_progress ||
 238                     objectid >= root->highest_objectid)
 239                         __btrfs_add_free_space(ctl, objectid, 1);
 240                 else
 241                         __btrfs_add_free_space(pinned, objectid, 1);
 242
 243                 mutex_unlock(&root->fs_commit_mutex);
 244         }
 245 }
 246
 247 /*
 248  * When a transaction is committed, we'll move those inode numbers which
 249  * are smaller than root->cache_progress from pinned tree to free_ino tree,
 250  * and others will just be dropped, because the commit root we were
 251  * searching has changed.
 252  *
 253  * Must be called with root->fs_commit_mutex held
 254  */
 255 void btrfs_unpin_free_ino(struct btrfs_root *root)
 256 {
 257         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 258         struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
 259         struct btrfs_free_space *info;
 260         struct rb_node *n;
 261         u64 count;
 262
 263         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 264                 return;
 265
 266         while (1) {
 267                 n = rb_first(rbroot);
 268                 if (!n)
 269                         break;
 270
 271                 info = rb_entry(n, struct btrfs_free_space, offset_index);
 272                 BUG_ON(info->bitmap); /* Logic error */
 273
 274                 if (info->offset > root->cache_progress)
 275                         goto free;
 276                 else if (info->offset + info->bytes > root->cache_progress)
 277                         count = root->cache_progress - info->offset + 1;
 278                 else
 279                         count = info->bytes;
 280
 281                 __btrfs_add_free_space(ctl, info->offset, count);
 282 free:
 283                 rb_erase(&info->offset_index, rbroot);
 284                 kfree(info);
 285         }
 286 }
 287
 288 #define INIT_THRESHOLD  (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
 289 #define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
 290
 291 /*
 292  * The goal is to keep the memory used by the free_ino tree won't
 293  * exceed the memory if we use bitmaps only.
 294  */
 295 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
 296 {
 297         struct btrfs_free_space *info;
 298         struct rb_node *n;
 299         int max_ino;
 300         int max_bitmaps;
 301
 302         n = rb_last(&ctl->free_space_offset);
 303         if (!n) {
 304                 ctl->extents_thresh = INIT_THRESHOLD;
 305                 return;
 306         }
 307         info = rb_entry(n, struct btrfs_free_space, offset_index);
 308
 309         /*
 310          * Find the maximum inode number in the filesystem. Note we
 311          * ignore the fact that this can be a bitmap, because we are
 312          * not doing precise calculation.
 313          */
 314         max_ino = info->bytes - 1;
 315
 316         max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
 317         if (max_bitmaps <= ctl->total_bitmaps) {
 318                 ctl->extents_thresh = 0;
 319                 return;
 320         }
 321
 322         ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
 323                                 PAGE_CACHE_SIZE / sizeof(*info);
 324 }
 325
 326 /*
 327  * We don't fall back to bitmap, if we are below the extents threshold
 328  * or this chunk of inode numbers is a big one.
 329  */
 330 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
 331                        struct btrfs_free_space *info)
 332 {
 333         if (ctl->free_extents < ctl->extents_thresh ||
 334             info->bytes > INODES_PER_BITMAP / 10)
 335                 return false;
 336
 337         return true;
 338 }
 339
 340 static struct btrfs_free_space_op free_ino_op = {
 341         .recalc_thresholds      = recalculate_thresholds,
 342         .use_bitmap             = use_bitmap,
 343 };
 344
 345 static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
 346 {
 347 }
 348
 349 static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
 350                               struct btrfs_free_space *info)
 351 {
 352         /*
 353          * We always use extents for two reasons:
 354          *
 355          * - The pinned tree is only used during the process of caching
 356          *   work.
 357          * - Make code simpler. See btrfs_unpin_free_ino().
 358          */
 359         return false;
 360 }
 361
 362 static struct btrfs_free_space_op pinned_free_ino_op = {
 363         .recalc_thresholds      = pinned_recalc_thresholds,
 364         .use_bitmap             = pinned_use_bitmap,
 365 };
 366
 367 void btrfs_init_free_ino_ctl(struct btrfs_root *root)
 368 {
 369         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 370         struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
 371
 372         spin_lock_init(&ctl->tree_lock);
 373         ctl->unit = 1;
 374         ctl->start = 0;
 375         ctl->private = NULL;
 376         ctl->op = &free_ino_op;
 377
 378         /*
 379          * Initially we allow to use 16K of ram to cache chunks of
 380          * inode numbers before we resort to bitmaps. This is somewhat
 381          * arbitrary, but it will be adjusted in runtime.
 382          */
 383         ctl->extents_thresh = INIT_THRESHOLD;
 384
 385         spin_lock_init(&pinned->tree_lock);
 386         pinned->unit = 1;
 387         pinned->start = 0;
 388         pinned->private = NULL;
 389         pinned->extents_thresh = 0;
 390         pinned->op = &pinned_free_ino_op;
 391 }
 392
 393 int btrfs_save_ino_cache(struct btrfs_root *root,
 394                          struct btrfs_trans_handle *trans)
 395 {
 396         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
 397         struct btrfs_path *path;
 398         struct inode *inode;
 399         struct btrfs_block_rsv *rsv;
 400         u64 num_bytes;
 401         u64 alloc_hint = 0;
 402         int ret;
 403         int prealloc;
 404         bool retry = false;
 405
 406         /* only fs tree and subvol/snap needs ino cache */
 407         if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
 408             (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
 409              root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
 410                 return 0;
 411
 412         /* Don't save inode cache if we are deleting this root */
 413         if (btrfs_root_refs(&root->root_item) == 0)
 414                 return 0;
 415
 416         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
 417                 return 0;
 418
 419         path = btrfs_alloc_path();
 420         if (!path)
 421                 return -ENOMEM;
 422
 423         rsv = trans->block_rsv;
 424         trans->block_rsv = &root->fs_info->trans_block_rsv;
 425
 426         num_bytes = trans->bytes_reserved;
 427         /*
 428          * 1 item for inode item insertion if need
 429          * 4 items for inode item update (in the worst case)
 430          * 1 items for slack space if we need do truncation
 431          * 1 item for free space object
 432          * 3 items for pre-allocation
 433          */
 434         trans->bytes_reserved = btrfs_calc_trans_metadata_size(root, 10);
 435         ret = btrfs_block_rsv_add(root, trans->block_rsv,
 436                                   trans->bytes_reserved,
 437                                   BTRFS_RESERVE_NO_FLUSH);
 438         if (ret)
 439                 goto out;
 440         trace_btrfs_space_reservation(root->fs_info, "ino_cache",
 441                                       trans->transid, trans->bytes_reserved, 1);
 442 again:
 443         inode = lookup_free_ino_inode(root, path);
 444         if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
 445                 ret = PTR_ERR(inode);
 446                 goto out_release;
 447         }
 448
 449         if (IS_ERR(inode)) {
 450                 BUG_ON(retry); /* Logic error */
 451                 retry = true;
 452
 453                 ret = create_free_ino_inode(root, trans, path);
 454                 if (ret)
 455                         goto out_release;
 456                 goto again;
 457         }
 458
 459         BTRFS_I(inode)->generation = 0;
 460         ret = btrfs_update_inode(trans, root, inode);
 461         if (ret) {
 462                 btrfs_abort_transaction(trans, root, ret);
 463                 goto out_put;
 464         }
 465
 466         if (i_size_read(inode) > 0) {
 467                 ret = btrfs_truncate_free_space_cache(root, trans, inode);
 468                 if (ret) {
 469                         if (ret != -ENOSPC)
 470                                 btrfs_abort_transaction(trans, root, ret);
 471                         goto out_put;
 472                 }
 473         }
 474
 475         spin_lock(&root->cache_lock);
 476         if (root->cached != BTRFS_CACHE_FINISHED) {
 477                 ret = -1;
 478                 spin_unlock(&root->cache_lock);
 479                 goto out_put;
 480         }
 481         spin_unlock(&root->cache_lock);
 482
 483         spin_lock(&ctl->tree_lock);
 484         prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
 485         prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
 486         prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
 487         spin_unlock(&ctl->tree_lock);
 488
 489         /* Just to make sure we have enough space */
 490         prealloc += 8 * PAGE_CACHE_SIZE;
 491
 492         ret = btrfs_delalloc_reserve_space(inode, prealloc);
 493         if (ret)
 494                 goto out_put;
 495
 496         ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
 497                                               prealloc, prealloc, &alloc_hint);
 498         if (ret) {
 499                 btrfs_delalloc_release_space(inode, prealloc);
 500                 goto out_put;
 501         }
 502         btrfs_free_reserved_data_space(inode, prealloc);
 503
 504         ret = btrfs_write_out_ino_cache(root, trans, path, inode);
 505 out_put:
 506         iput(inode);
 507 out_release:
 508         trace_btrfs_space_reservation(root->fs_info, "ino_cache",
 509                                       trans->transid, trans->bytes_reserved, 0);
 510         btrfs_block_rsv_release(root, trans->block_rsv, trans->bytes_reserved);
 511 out:
 512         trans->block_rsv = rsv;
 513         trans->bytes_reserved = num_bytes;
 514
 515         btrfs_free_path(path);
 516         return ret;
 517 }
 518
 519 static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
 520 {
 521         struct btrfs_path *path;
 522         int ret;
 523         struct extent_buffer *l;
 524         struct btrfs_key search_key;
 525         struct btrfs_key found_key;
 526         int slot;
 527
 528         path = btrfs_alloc_path();
 529         if (!path)
 530                 return -ENOMEM;
 531
 532         search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
 533         search_key.type = -1;
 534         search_key.offset = (u64)-1;
 535         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
 536         if (ret < 0)
 537                 goto error;
 538         BUG_ON(ret == 0); /* Corruption */
 539         if (path->slots[0] > 0) {
 540                 slot = path->slots[0] - 1;
 541                 l = path->nodes[0];
 542                 btrfs_item_key_to_cpu(l, &found_key, slot);
 543                 *objectid = max_t(u64, found_key.objectid,
 544                                   BTRFS_FIRST_FREE_OBJECTID - 1);
 545         } else {
 546                 *objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
 547         }
 548         ret = 0;
 549 error:
 550         btrfs_free_path(path);
 551         return ret;
 552 }
 553
 554 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
 555 {
 556         int ret;
 557         mutex_lock(&root->objectid_mutex);
 558
 559         if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
 560                 ret = btrfs_find_highest_objectid(root,
 561                                                   &root->highest_objectid);
 562                 if (ret)
 563                         goto out;
 564         }
 565
 566         if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
 567                 ret = -ENOSPC;
 568                 goto out;
 569         }
 570
 571         *objectid = ++root->highest_objectid;
 572         ret = 0;
 573 out:
 574         mutex_unlock(&root->objectid_mutex);
 575         return ret;
 576 }